The eggshell (chorion) proteins of silkmoths are encoded in informational multigene families. The multiple proteins of each major size class are highly homologous, yet each one is produced at a characteristic and different period of development. The structure and organization of the chorion genes are being studied at the nucleic acid level. In parallel, we propose to extend our initial protein purification, characterization and sequencing studies, so as to be able to understand the evolutionary mechanisms which have diversified these proteins and to construct evolutionary dendrograms relating them to each other. In conjunction with our knowledge of the developmental program of protein synthesis and the direct gene-level studies, this approach will allow us to begin interpreting the pattern of chorion gene organization, and the nature of the DNA between linked genes, in terms of two important but distinct biological processes: developmental regulation and evolutionary change. We will also begin a structure-function analysis of several chorion proteins, by characterizing the structures with which each is associated, so as to understand the functional consequences of evolutionary diversification.